Electrical baseboard heaters are familiarly used for convection air heating. If designed to be portable, they are conventionally equipped with an exterior handle. They are made in a variety of lengths, depending upon their voltage. Elongated resistance elements may be used, having terminals at their opposite ends; these are conventionally surrounded by tubular reservoirs for containing a heat transfer liquid, with vertical fins on its exterior. Such heaters may be subject to stresses and distortion during shipment and handling; and the portable units are particularly subject to abuse.